Relay



Jan. 30, 1951 J. E. MossMAN ETAL 2,539,547

RELAY Filed June 13, 1945 2 Sheets-Sheet 1 fnz/erzr: fahrt E /YamanJames I5-750771 Jam 30, 1951 JQ E. M'ossMAN x-:T AL 2,539,547

RELAY Filed June 13, 1945 2 Sheets-Sheet 2 Patented Jan. 30, 1951 RELAYJohn E. Mossman and James D. Elsom, Chicago, Ill., assignors to C. P.Clare & Co., Chicago, Ill., a corporation of Illinois Application June13, 1945, Serial No. 599,132

1 Claim.

The present invention relates to relays, and has for its principalobject the provision of a relay embodying a novel combination of partswhereby the necessity of springs to retract the armature is eliminated.It is customary in the manufacture of relays to depend upon springs orgravity to retract the armature when it is released by cutting olf thecurrent through the coil of the relay.

It is a further purpose of our invention to provide a relay constructionthat is particularly advantageous in giving higher rates of accelerationfor breaking and making of contacts controlled by the armature. Althoughit is not limited thereto, our invention is particularly useful inalternating current relays for controlling sealed power units such asmotors that are operated in sealed space over long periods of timewithout being opened for cleaning or inspection. In such environments itis essential that the relays be as free of sparking at the contacts aspossible. In making or breaking a circuit for a motor or like powerdevice, the sparking can be greatly minimized by speeding up the openingor closing of the contacts.

Our invention makes possible an increase in the speed of movement of thecontacts at the critical point in their action. It is also essential inequipment of the character referred to above, that the opening andclosing ofthe contacts be quite positive in character. It is well knownthat springs after repeated operations tend to crystalllze or weaken,and this oftentimes results in failure of the equipment in a progressiveway that is particularly damaging to the more expensive parts such asthe motors.

Our invention contemplates the provision of a relay wherein both frontand back contacts are closed with the same improvement in operation.However the invention is not limited in this manner since it may workequally well with only a front contact or a back contact. Likewise itmay control a multiplicity of contacts with the same positive operation.The invention is embodied in an alternating current relay that utilizesthe magnetic attraction of the armature by a permanent magnet forretracting the armature and holding it away from the core of the relay.The movable contacts are carried by a contact lever which is pivoted butwhich is not biased to any particular position by means of a spring. Thelever may or may not be resilient depending upon the particularinstallation.

It is also a purpose of our invention to provide a novel relayconstruction embodying a coil and core for attracting the armature uponenergization of the coil and a permanent magnet retracting the armaturewhen the coil is de-energized. the entire assembly being sealed in ashell of non-conducting, non-magnetic material of such a nature thatcertain parts such as the permanent magnet are moulded in the materialitself.

The nature and advantages of our invention will appear more fully fromthe following description and the accompanying drawings Wherein apreferred form of the invention is disclosed. It should be understood,however, that the drawings and description are illustrative only, andare not to be taken as limiting the invention except insofar as it islimited by the claim.

In the drawings:

Figure 1 is a longitudinal sectional view through a relay embodying ourinvention.

Figure 2 is a view looking at the mechanical parts of the relay from theline 2-2 of Figure 1.

Figure 3 is a sectional view taken on the line 3-3 of Figure l.

Figure 4 is a sectional view taken on the line 4 4 of Figure 1.

Figure 5 is a sectional view taken on the line 5 5 of Figure 1.

Figure 6 is a perspective view of the armature of the relay.

Figure 7 is an exploded perspective view showing the core constructionof the relay, and

Figure 8 is a perspective view of an additional shading element that maybe used under certain conditions.

Referring now to the drawings, the present invention is embodied in arelay wherein numeral I0 refers to the core, the armature is shown at II, and a shell I2 is secured to the core at one end and extends upwardto a point substantially ush with the end of the core adjacent thearmature. A coil I3 is wound on the core and has its terminal leads I4and I5 extending downwardly through the shell I2. The core, the armatureand the shell preferably are constructed of silicon steel which isgenerally used in devices of this character, because of its lowhysteresis and eddy current losses. In order to further improve theefliciency of the device, we provide slots I6 at intervals about thecore, and similar slots Il at intervals about the shell I2. The armatureII may also be slotted as indicated at I8 for the same reason.

The relay includes, also, a suitable means for retracting the armatureII. This means comprises a permanent magnet I9 which is on the oppositeside of the armature from the core I0 so that the attraction of thepermanent magnet is continually present, tending to move the armatureaway from the end face of the core and the shell. The armature is madeto perform its function of opening and closing electrical contacts bymeans of a stem 20 of non-magnetic metal such as brass or stainlesssteel. The stem is riveted or otherwise firmly secured to the armatureand extends through the core Io to project a substantial distance belowthe lower end of the core. At its lower end the stem has a reduced neckportion 2| which ts in a slot 22 of a contact carrying lever 23. 'I'helever 23 is pivoted on a pivot pin 24 and it carries a contact element25 at its free end. The lever 23 is connected by suitable leads 26 and21 to a plug 28 so that a source of current may be connected to thecontact 25. The contact 25 cooperates with two opposed stationarycontacts 29 and 3@ so that when the lever arm 23 is moved downwardly byenergization of the coil I3, and the resultant attraction of thearmature il by the core i@ and the shell I2, a circuit is completed atthe contacts 25 and 30. When the coil I3 is de-energized, the attractionof the permanent magnet i9 for the armature II moves the armature andits stem 2li upwardly to cause the lever 23 to swing the contact 25 awayfrom the contact 3d, and into engagement with the contact 29 to completeanother circuit.

The contacts 29 and 30 are secured byterminal strips 3| and 32 upon abase plate 33 of insulating material. Wiring tips 34 and 35 are providedfor these terminals so that they may be connected to plugs 36 which aresimilar to the plug 25. Two other plugs, 31, are utilized to connect theleads I4 and I 5 from the coil i3 to a source of current. 'I'he leadwires, such as 21, Btl and 39 for connecting the coil and the contactsin the circuit, extend down inside the hollow plugs such as 28, 36 and31, and are sealed in place by dipping the open ends of the plugs insolder so that the solder lls up the end of the plug as shown at 40 inFigure 1 of the drawings.

The mounting plate 33 is secured in a housing 4I by pressing it againsta shoulder d2 in the housing, and cementng the plate 33 and the housingtogether. The plugs are carried by a mounting plate 43 which is seatedin the open end of the housing 4i against a shoulder ld, and alsocemented in place. The housing di is desirably circular in cross sectionwith the lower portion housing the contacts being somewhat larger indiameter than the upper portion, so as to provide the shoulder 42. Thishousing is preferably constructed of a transparent insulating material.For example, a polystyrene resin or a similar material is satisfactoryfor our purpose. The plates 33 and 43 are constructed of the samematerial, and the cement used is such that it permanently bonds theplate to the shell.

In making up the shell 4I the permanent magnet I9 which is preferably ofthe material sold under the trade name Alnico is moulded in the shellitself. The magnet is formed with a tapering rim I9a, and is projectedslightly beyond the inner surface of the shell, so as to give adequateclearance for engagement between the magnet and the armature. Magnetsmade of the imaterial referred to above have the capacity to retaintheir magnetism for years with very little change in the strength of themagnet. These magnets are made and aged until the magneticcharacteristics thereof are substantially uniform. 'I'hey can withstandthe necessary heat for moulding the polystyrene shell without adverseell'ects upon their magnetic qualities. Any effect of the repeatedmagnetization of the core upon the permanent magnet is substantiallyeliminated by the core and shell construction used which provides asubstantially closed magnetic circuit about the coil.

As shown, this relay is constructed for use on alternating current. Itis therefore provided with a shading coil 45 of copper. The coil isformed to flt in a slot 46 in the upper end of the core I0, and ispressed or staked in place. It will be noted that the shading coil hasan aperture 41 through which the stem 20 passes. For some purposes it isdesirable to have a greater shading effect, and in that case we preferto employ a second shading coil 48, which cooperates with the shell I2.This shading coil comprises a copper stamping of substantially the shapeshown in Figure 8 of the drawings. The shell I2 is notched as shown at49 and 50 to receive the web portion 5| of the shading coil 48. This webportion is separated from the rim portion of the shading coil by a slot52 that receives the edge of the shell I2 between the slots 49 and 50.The shading coll 48 is secured in place by staking it at the edges ofthe notches 49 and 50.

The shell I2 is xed to the plate 33 by a pair of screws 53. The terminalstrips 3l and 32 are riveted to the plate 33. The coil terminals I4 andI5 have sleeves 54 and 55 thereon, and these sleeves extend through theplate 33 and the shell i2 so as to insulate the coil terminals from theother parts of the relay.

The particular advantages of our improved relay lie in the improvedacceleration of the movement of the armature II when it is attracted bythe core ill, and when it is retracted by the magnet i9. In the casewhere the armature is in a retracted position the stem 20 has moved thelever 23 to bring the contact 25 against the contact Z9. We prefer tomake the lever 23 of a material having a slight resiliency, for examplea nickel silver alloy so that the lever can yield sufliciently when thearmature is retracted to bring the armature in close juxtaposition tothe permanent magnet i9. Now when the coil I3 is energized sufficientlyto initiate movement of the armature il, the resultant action is a rapiddeceleration of the attraction of the permanent magnet while theattraction of the core of the relay is increasing. This is because theattraction of a permanent magnet varies inversely as the square of thedistance from the magnet to the armature. Thus when the armature hasmoved two thousandths of an inch from its resting position with respectto the permanent mag- Y net, the attraction of the permanent magnet forthe armature is one-quarter that when the armature was positionfd onethousandth of an inch from the magnet. The result upon the movement ofthe armature il is a very rapid acceleration. This is translated to thecontact 25 through the stem 20 and the lever 23 so as to break thecontact away from the stationary contact 29, much more quickly than itwould be broken if the armature were spring retracted or gravityretracted. When the armature is retracted by a spring, the spring mustnecessarily increasingly oppose the movement of the armature by thecore, and that is the direct opposite of the effect of the permanentmagnet. Much the same result is obtained upon the return stroke becausewhen the armature is released by the core sufficiently for the permanentmagnet to attract it, the movement of the armature is immediatelyaccelerated at an increasing rate by its approach to the permanentmagnet.

The construction of our relay, also, is particlularly advantageous whereit is necessary for ment, is adequate for many years of operation of therelay for its intended purpose.

It is believed that the nature and advantages o! our invention aresumciently explained in the foregoing description to enable thoseskilled in the art to practice the invention, and to appreciate theadvantages thereof.

Having thus described our invention, we claim: 1

A relay of the character described comprising a cup shaped sealedhousing having in one end thereof a permanent magnet with a fiat facefacing toward the other end thereof, a disc shaped armature adjacentsaid permanent magnet, a core of magnetic material tlxed in the housingwith its end face closely spaced with respect to said permanent magnetand on the opposite side of the amature from the magnet and holding theamature within the attraction range of the permanent magnet, whereby thepermanent magnet will attract the amature when the core is de-energized,an energizing winding on the core, circuit control contacts in thehousing, a guide stem for said armature extending through the core andoperably connected to said contacts for actuating the same, and terminalleads for said circuit control contacts and said energizing windingextending through the end of the housing opposite the permanent magnet,said terminal leads being also sealed in the housing whereby all theoperative parts of the device are completely sealed.

JOHN E. MOSSMAN. JAMES D. ELSOM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 428,650 'Ihomson May 27, 1890506,282 Timmins Oct. 10, 1893 685,431 Pearson Oct. 29, 1901 1,081,884Bertagnolli Dec. 16, 1913 1,086,985 Bliss Feb. 10, 1914 1,215,422Spangler Feb. 13, 1917 1,987,144 Dinkel, Jr. Jan. 8, 1935 2,369,331Baker Feb. 13, 1945 2,389,592 Bucklen, Jr. et al. Nov. 27, 19452,450,924 smqen oct. 12, 194s FOREIGN PATENTS Number Country Date407,052 Germany Dec. 10, 1924 434,077 Great Britain Aug. 26 1935

